The present invention relates to a technique for using multiple irradiation sources to detect and characterize chemical and biological agents.
Various techniques have previously been considered for detecting illegal and dangerous items, such as drugs, explosives, weapons, and the chemical and biological substances/agents within such items, for implementing crime prevention, police officer protection, security, and counter-terrorism initiatives. In the case of detecting certain types of chemical and biological substances, some known techniques require taking a physical sample of a substance, chemically breaking down (e.g., xe2x80x9ccookingxe2x80x9d) the substance to measure physical characteristics thereof, and comparing the measured physical characteristics with those of reference substances. Such invasive detection techniques create a likelihood of endangering personnel through exposure to hazards while retrieving the substance to be analyzed, and are slow and limited in terms of detection capability because only physically retrievable substances can be analyzed. Another known detection technique employs spectroscopy, using non-hardened CO2 lasers and the like, to optically detect or characterize substances. This technique also has drawbacks, however, because the requisite lasers are large and expensive. Furthermore, the inventor of this application has found that, although a generally accurate technique for characterizing substances/agents, laser spectroscopy in some instances will fail to recognize subtle differences between the makeup of substances/agents, thereby failing to ensure against false alarms and errors.
This invention presents an approach that integrates three or more sources having different nature to irradiate a region and detect, as well as characterize, present chemical or biological agents based on returned signals. More particularly, the present approach integrates spectroscopy, spectroscopic acoustic interferometry, and swept frequency acoustic interferometry to instigate and detect physical and mass changes in irradiated chemical and biological agents. In its most basic level, the inventive approach integrates a tunable wavelength laser with a moderately fixed wavelength laser and an acoustic generator to simultaneously irradiate a region that is to be monitored for chemical or biological agents. Such a system is used to generate databases of response profiles for chemical and biological agents. Such a system is also used with an already obtained database of response profiles and optimization or artificial intelligence routines to identify targets of unknown nature.
The inventive approach has the advantage of enhanced signal discrimination because of the differing response of different chemicals and biological agents to multiple simultaneous irradiations. The response profile, as a function of frequencies of the three simultaneous irradiations, facilitates discrimination between related but different chemical and biological agents. Also, since the irradiations can be directed to distant regions and the return signal detected from these distant regions, the present approach has the advantage of keeping the system operator safe from unnecessary exposure to potentially unsafe chemical or biological agents.